1. Field of the Invention
The invention relates to a barcode processing apparatus and barcode processing method, which recognize a barcode printed on, e.g., a postal matter.
2. Description of the Related Art
In the field of postal matter processing, it is known that a barcode corresponding to address information is printed on a postal matter. For example, a mail processing machine reads an image of each postal matter which is conveyed at high speed, recognizes address information in the image, and prints a barcode corresponding to the recognized address information on the postal matter. Alternatively, when the mail processing machine cannot recognize address information, an operator visually recognizes a displayed postal matter image and inputs the address information. In response to this, the mail processing machine prints a barcode corresponding to the input address information on the postal matter.
After barcodes are printed on postal matters, the postal matters are processed based on the barcodes. For example, a mail sorting machine reads barcodes printed on postal matters, and sorts the postal matters based on the read barcodes.
In order to accurately sort the postal matters, it is required to accurately read barcodes from postal matter images. As a technique for accurately processing barcodes, for example, Jpn. Pat. Appln. KOKAI Publication Nos. 2005-266907 (reference 1) and 2008-84218 (reference 2) disclose a barcode detection technique for detecting a barcode from a postal matter image and a barcode reading technique for reading a barcode.
However, it is difficult for the aforementioned techniques to correctly recognize bars in a slant state printed on a postal matter.
For example, a mail processing apparatus prints a barcode on a postal matter, which is conveyed at high speed, using an ink-jet printer. For this reason, when adjustment of the postal matter convey speed and the ink-ejection timing of the ink-jet printer is insufficient, bars which configure a barcode are often printed in a tilted (slant) state. It is difficult for the aforementioned techniques to correctly recognize the bars in the slant state.
For example, reference 1 discloses a technique for detecting a barcode by filtering, but it does not disclose any technique about bar detection in the slant state. Also, patent reference 2 discloses technique that copes with a barcode in a skew state, but it does not disclose any technique about bar detection in the slant state.
Note that the barcode in the skew state means a barcode in which the arrangement of bars which configure the barcode are skewed with respect to the convey direction of a postal matter, i.e., a barcode which is entirely printed obliquely with respect to the convey direction of a postal matter. By contrast, a barcode configured by bars in the slant state means a barcode in a state in which respective bars that configure the barcode are slant with respect to the convey direction of a postal matter but the entire barcode is printed along the convey direction of the postal matter.